What you're asking for is not possible because of the security checks for user capabilities and admin referrer checks. It would be best for you to create a form on the front-end and use the wp_insert_post()
//Verify nonce and referrer
$args = array(
'post_status' => 'draft',
'post_content' => esc_html($content),
'post_title' => esc_attr($title)
$foo = wp_insert_post($args);
//If the post was inserted, wp_insert_post() will return the post ID of the new post
//Create your form with a hidden nonce field here.
- You absolutely need to use nonces anytime you accept input.\
- Use the built in Wordpress escaping functions to secure input data after you validate it. http://markjaquith.wordpress.com/2009/06/12/escaping-api-updates-for-wordpress-2-8/
I've built several forms like this using a static template as well as an AJAX version. It isn't that hard to do. Just make sure you take every precaution to verify the integrity of the data and hide the input form from evil doers.